tsc.c

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    1 /*-
    2  * Copyright (c) 1998-2003 Poul-Henning Kamp
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: releng/5.1/sys/amd64/amd64/tsc.c 114349 2003-05-01 01:05:25Z peter $
   27  */
   28 
   29 #include "opt_clock.h"
   30 
   31 #include <sys/param.h>
   32 #include <sys/systm.h>
   33 #include <sys/sysctl.h>
   34 #include <sys/time.h>
   35 #include <sys/timetc.h>
   36 #include <sys/kernel.h>
   37 #include <sys/power.h>
   38 #include <sys/smp.h>
   39 #include <machine/clock.h>
   40 #include <machine/md_var.h>
   41 #include <machine/specialreg.h>
   42 
   43 uint64_t        tsc_freq;
   44 int             tsc_is_broken;
   45 u_int           tsc_present = 1;
   46 
   47 #ifdef SMP
   48 static int      smp_tsc;
   49 SYSCTL_INT(_kern_timecounter, OID_AUTO, smp_tsc, CTLFLAG_RD, &smp_tsc, 0,
   50     "Indicates whether the TSC is safe to use in SMP mode");
   51 TUNABLE_INT("kern.timecounter.smp_tsc", &smp_tsc);
   52 #endif
   53 
   54 static  unsigned tsc_get_timecount(struct timecounter *tc);
   55 
   56 static struct timecounter tsc_timecounter = {
   57         tsc_get_timecount,      /* get_timecount */
   58         0,                      /* no poll_pps */
   59         ~0u,                    /* counter_mask */
   60         0,                      /* frequency */
   61          "TSC"                  /* name */
   62 };
   63 
   64 void
   65 init_TSC(void)
   66 {
   67         u_int64_t tscval[2];
   68 
   69         if (bootverbose)
   70                 printf("Calibrating TSC clock ... ");
   71 
   72         tscval[0] = rdtsc();
   73         DELAY(1000000);
   74         tscval[1] = rdtsc();
   75 
   76         tsc_freq = tscval[1] - tscval[0];
   77         if (bootverbose)
   78                 printf("TSC clock: %lu Hz\n", tsc_freq);
   79 
   80         if (tsc_freq != 0 && !tsc_is_broken) {
   81                 tsc_timecounter.tc_frequency = tsc_freq;
   82                 tc_init(&tsc_timecounter);
   83         }
   84 
   85         return;
   86 }
   87 
   88 static int
   89 sysctl_machdep_tsc_freq(SYSCTL_HANDLER_ARGS)
   90 {
   91         int error;
   92         uint64_t freq;
   93 
   94         if (tsc_timecounter.tc_frequency == 0)
   95                 return (EOPNOTSUPP);
   96         freq = tsc_freq;
   97         error = sysctl_handle_int(oidp, &freq, sizeof(freq), req);
   98         if (error == 0 && req->newptr != NULL) {
   99                 tsc_freq = freq;
  100                 tsc_timecounter.tc_frequency = tsc_freq;
  101         }
  102         return (error);
  103 }
  104 
  105 SYSCTL_PROC(_machdep, OID_AUTO, tsc_freq, CTLTYPE_LONG | CTLFLAG_RW,
  106     0, sizeof(u_int), sysctl_machdep_tsc_freq, "IU", "");
  107 
  108 static unsigned
  109 tsc_get_timecount(struct timecounter *tc)
  110 {
  111         return (rdtsc());
  112 }

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FreeBSD/Linux Kernel Cross Reference sys/amd64/amd64/tsc.c

FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/tsc.c